Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of total compensation cost recognized in the statement of operations

Total compensation cost recognized for all stock options and restricted stock units in the statements of operations for the years ended December 31, 2023 and 2022 is as follows (in thousands):

	Year Ended
	December 31,
	2023		2022
Research and development	$	5,806	$	5,364
Selling, general and administrative		9,757		9,526
Total	$	15,563	$	14,890

Schedule of weighted-average assumptions estimated at the date of grant using the Black-Scholes option pricing model

	2023				2022
Expected stock price volatility	99	-	104	%	103	-	116	%
Expected term of options	5.3	-	6.1	years	5.7	-	6.5	years
Risk‑free interest rate	3.35	-	4.82	%	1.65	-	4.46	%
Expected annual dividend yield			0	%			0	%

Schedule of unrecognized compensation expense expected to be recognized in future years

2024	$	12,690
2025		7,348
2026		1,549
2027		366
	$	21,953

Employee Stock Option

Summary of activity for all options

A summary of stock option activity for the years ended December 31, 2023 and 2022 is presented below (in thousands, except share and per share amounts):

		Weighted‑
		Average		Aggregate
		Exercise Price		Intrinsic
	Shares	Per Share		Value
Outstanding—December 31, 2021	4,738,855	$	12.23
Granted	2,026,981		8.77
Exercised	(238,312)		7.52
Forfeited	(415,816)		10.49
Expired	(381,489)		14.61
Outstanding—December 31, 2022	5,730,219	$	10.87
Granted	2,117,451		6.43
Exercised	(126,735)		6.35
Forfeited	(267,239)		8.34
Expired	(288,715)		13.34
Outstanding—December 31, 2023	7,164,981	$	9.64	$	17,854
Exercisable—December 31, 2023	4,620,748	$	10.64	$	9,292

Restricted Stock and Restricted Stock Units

Summary of activity for restricted stock and restricted stock units

		Weighted‑average
		Grant Date
	Shares	Fair Value per Share
Outstanding—December 31, 2021	26,025	$	12.75
Granted	809,028		8.49
Vested	(37,450)		11.19
Forfeited	(125,627)		9.04
Outstanding—December 31, 2022	671,976		8.39
Granted	1,004,310		6.17
Vested	(262,819)		8.26
Forfeited	(141,573)		6.61
Outstanding—December 31, 2023	1,271,894	$	6.86